Created Unassigned: Disconnect hangs for several minutes [2627]

Hi all,

when disconnecting the SftpClient it hangs for several minutes.
While investigating the issue, I found that the cause of this issue is situated in the SocketDisconnect method in Session.cs.


``` C#
partial void SocketDisconnect()
{
_socket.Disconnect(true);
}
```

Is there a reason why the Disconnect method is used with the parameter 'true', because the socket is never used again after the disconnect. It is even disposed after the disconnect.

Best regards